This invention relates to a percussion power tool apparatus which includes a body mounting an impacting tool, the tool being moved outwardly of the body e.g. by an impacting piston impacting the tool. One such percussion power tool apparatus is known as a breaker and is used to break concrete, paving or another structure or particle e.g. the ground. In a breaker, the impacting tool may be impacted by the impacting piston several times each second, and in one type of breaker apparatus, the impacting piston is moved by fluid pressure acting within a cylinder containing the impacting piston. The impacting tool, upon striking the ground or another structure or particle to be broken, reacts by moving back inwardly of the body.
The operating cycle of the percussion power tool apparatus therefore gives rise to various vibrations, some of which are transmitted via the impacting tool to effect a breaking or other impacting operation, to break the ground or other structure or particles.